Oxylipin metabolism is controlled by mitochondrial β-oxidation during bacterial inflammation

Oxylipins are potent biological mediators requiring strict control, but how they are removed en masse during infection and inflammation is unknown. Here we show that lipopolysaccharide (LPS) dynamically enhances oxylipin removal via mitochondrial β-oxidation. Specifically, genetic or pharmacological targeting of carnitine palmitoyl transferase 1 (CPT1), a mitochondrial importer of fatty acids, reveal that many oxylipins are removed by this protein during inflammation in vitro and in vivo. Using stable isotope-tracing lipidomics, we find secretion-reuptake recycling for 12-HETE and its intermediate metabolites. Meanwhile, oxylipin β-oxidation is uncoupled from oxidative phosphorylation, thus not contributing to energy generation. Testing for genetic control checkpoints, transcriptional interrogation of human neonatal sepsis finds upregulation of many genes involved in mitochondrial removal of long-chain fatty acyls, such as ACSL1,3,4, ACADVL, CPT1B, CPT2 and HADHB. Also, ACSL1/Acsl1 upregulation is consistently observed following the treatment of human/murine macrophages with LPS and IFN-γ. Last, dampening oxylipin levels by β-oxidation is suggested to impact on their regulation of leukocyte functions. In summary, we propose mitochondrial β-oxidation as a regulatory metabolic checkpoint for oxylipins during inflammation.

Downregulating carnitine palmitoyl transferase 1 affects disease progression in the SOD1 G93A mouse model of ALS

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease characterized by death of motor neurons. The etiology and pathogenesis remains elusive despite decades of intensive research. Herein, we report that dysregulated metabolism plays a central role in the SOD1 G93A mouse model mimicking ALS. Specifically, we report that the activity of carnitine palmitoyl transferase 1 (CPT1) lipid metabolism is associated with disease progression. Downregulation of CPT1 activity by pharmacological and genetic methods results in amelioration of disease symptoms, inflammation, oxidative stress and mitochondrial function, whereas upregulation by high-fat diet or corticosterone results in a more aggressive disease progression. Finally, we show that downregulating CPT1 shifts the gut microbiota communities towards a protective phenotype in SOD1 G93A mice. These findings reveal that metabolism, and specifically CPT1 lipid metabolism plays a central role in the SOD1 G93A mouse model and shows that CPT1 might be a therapeutic target in ALS.

Carnitine palmitoyl transferase 1A is a novel diagnostic and predictive biomarker for breast cancer

Background Carnitine palmitoyl transferase 1A (CPT1A), the key regulator of fatty acid oxidation, contributes to tumor metastasis and therapeutic resistance. We aimed to identify its clinical significance as a biomarker for the diagnosis and prediction of breast cancer. Methods Western blot, ELISA and in silico analysis were used to confirm CPT1A levels in breast cancer cell lines, cell culture medium and breast cancer tissues. Four hundred thirty breast cancer patients, 200 patients with benign breast disease, and 400 healthy controls were enrolled and randomly divided into a training set and a test set with a 7:3 ratio. Training set was used to build diagnostic models and 10-fold cross validation was used to demonstrate the performance of the models. Then test set was aimed to validate the effectiveness of the diagnostic models. ELISA was conducted to detect individual serum CPT1A levels. Receiver operating characteristic (ROC) curves were generated, and binary logistic regression analyses were performed to evaluate the effectiveness of CPT1A as a biomarker in breast cancer diagnosis. CPT1A levels between post-operative and pre-operative samples were also compared. Results CPT1A was overexpressed in breast cancer tissues, cell lines and cell culture medium. Serum CPT1A levels were higher in breast cancer patients than in controls and were significantly associated with metastasis, TNM stage, histological grading and molecular subtype. CPT1A levels were decreased in post-operative samples compared with paired pre-operative samples. Moreover, CPT1A exhibited a higher efficacy in differentiating breast cancer patients from healthy controls (training set: area under the curve, AUC, 0.892, 95% CI, 0.872–0.920; test set, AUC, 0.904, 95% CI, 0.869–0.939) than did CA15–3, CEA, or CA125. Conclusion CPT1A is overexpressed in breast cancer and can be secreted out of breast cancer cell. Serum CPT1A is positively associated with breast cancer progression and could serve as an indicator for disease monitoring. Serum CPT1A displayed a remarkably high diagnostic efficiency for breast cancer and could be a novel biomarker for the diagnosis of breast cancer.

Metabolic programming of adipose tissue in female C57Bl 6 mice offspring by maternal high fat feeding and obesity results in greater adaptability to dietary fat content and resistance to high fat diet-induced glucose intolerance compared to male mice

Maternal lifestyle influence may be a factor in the worldwide prevalence of obesity and its complications, including diabetes. Studies investigating the effect of the perinatal maternal environment have produced a range of results, sometimes diametrically opposite. The present study was designed to investigate how obesity and weight gain in pregnant mice affects energy balance, body composition and glucose homeostasis in their offspring, both at a young age on standard diet and when older and fed a high-fat diet. At six weeks of age both male and female offspring from mothers fed a high fat diet had a shorter body length than those from mothers fed standard chow. In contrast to males, female offspring also contained a higher proportion of fat and had elevated circulating leptin and adiponectin. Their gonadal fat pads were heavier and contained larger adipocytes, whereas male offspring had proportionally more smaller adipocytes. Six-week-old female, but not male, offspring had increased gonadal fat gene expression of acetyl CoA carboxylase 1, the rate-limiting step in lipid biosynthesis, and decreased gene expression of carnitine palmitoyl transferase 1, the rate-limiting step in fatty acid oxidation. Maternal high fat diet had no effect on glucose tolerance in six-week-old mice, but this was achieved with higher insulin levels in females. Contrastingly, when the offspring were fed a high fat diet for three months, female, but not male, offspring were leaner than those from mothers fed standard chow. Their gonadal fat depots were lighter and the adipocytes were smaller. Female, but not male, offspring fed high fat diet had decreased gonadal fat gene expression of acetyl CoA carboxylase 1, and increased gene expression of carnitine palmitoyl transferase 1. High fat diet-induced glucose intolerance and elevated plasma insulin concentration were improved in female, but not male, offspring. Plasma leptin and adiponectin remained higher in female offspring on high fat diet with resistin levels being lower. These results suggest that the gonadal fat of female offspring is more adaptable to different levels of dietary fat exposure, increasing storage when levels are low and increasing oxidation when levels are high. This may help female offspring be more resistant to the detrimental effects of high fat diet than male mice.

Dysregulation of metabolic pathways by carnitine palmitoyl-transferase 1 plays a key role in central nervous system disorders: experimental evidence based on animal models

The etiology of CNS diseases including multiple sclerosis, Parkinson’s disease and amyotrophic lateral sclerosis remains elusive despite decades of research resulting in treatments with only symptomatic effects. In this study, we provide evidence that a metabolic shift from glucose to lipid is a key mechanism in neurodegeneration. We show that, by downregulating the metabolism of lipids through the key molecule carnitine palmitoyl transferase 1 (CPT1), it is possible to reverse or slowdown disease progression in experimental models of autoimmune encephalomyelitis-, SOD1G93A and rotenone models, mimicking these CNS diseases in humans. The effect was seen both when applying a CPT1 blocker or by using a Cpt1a P479L mutant mouse strain. Furthermore, we show that diet, epigenetics, and microbiota are key elements in this metabolic shift. Finally, we present a systemic model for understanding the complex etiology of neurodegeneration and how different regulatory systems are interconnected through a central metabolic pathway that becomes deregulated under specific conditions.